Pension Benefits (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Components of Net Periodic Benefit Costs for Both Pension Plans
Defined Benefit Plan, Service Cost	$ 1,515,000	$ 1,052,000	$ 2,465,000	$ 1,900,000
Defined Benefit Plan, Interest Cost	393,000	312,000	689,000	592,000
Defined Benefit Plan, Expected Return on Plan Assets	(352,000)	(281,000)	(572,000)	(440,000)
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)	9,000	0	9,000	0
Defined Benefit Plan, Amortization of Gains (Losses)	293,000	111,000	394,000	202,000
Defined Benefit Plan, Net Periodic Benefit Cost	1,858,000	1,194,000	2,985,000	2,254,000
Percentage in excess of the greater of the benefit obligation or the market-related value of assets, gain and losses amortized (as a percent)	10.00%
Required contribution to Qualified Pension Plan for the current fiscal year	5,400,000		5,400,000
Contribution to the Qualified Pension Plan in the current fiscal year			$ 4,600,000